Ectemnius

Distinguished from similar genera in tribe Crabronini (Anacrabro, Lestica, Crabro) by the convex or flat underside of the abdomen; Anacrabro has a very concave abdominal underside. Species-level identification requires examination of antennal structure in males, mandibular dentition, and precise pattern of yellow markings.

Small to medium-sized wasps with black bodies and yellow markings on scapes, pronotum, tibiae, and tergites. The clypeus is covered with shining silver hairs. Unusually for aculeate wasps, males lack an additional antennal segment, with both sexes possessing 12 antennal segments. Some species exhibit reduced yellow markings on specific tergites or longitudinal striations on the mesonotum.

Woodlands, gardens, farmland, and forested areas. Nests are constructed in pre-existing cavities in dead wood including tree stumps, fallen trunks, rotting logs, standing dead wood, fence posts, and occasionally building timbers.

Worldwide distribution with greatest diversity in the Holarctic region; common across Europe and North America. Australia has only two species.

Flight period varies by species; E. continuus active from early May to late September (likely bivoltine in southern UK); E. lituratus has a later flight period from June to September. Most species univoltine.

Adult females hunt medium-sized Diptera (flies) including families Syrphidae, Muscidae, Calliphoridae, Tabanidae, Therevidae, Anthomyiidae, and Cordyluridae. Adults visit flowers of umbellifers (wild carrot, hogweed, wild parsnip, angelica, cow parsley, fennel, water-dropwort) for nectar.

• Anthomyiidae - preyhunted by E. lituratus
• Cordyluridae - preyhunted by E. lituratus
• Syrphidae - preyhunted by E. continuus
• Muscidae - preyhunted by E. continuus
• Calliphoridae - preyhunted by E. continuus
• Tabanidae - preyhunted by E. continuus
• Therevidae - preyhunted by E. continuus

Univoltine or bivoltine depending on species and latitude. Females construct nests in dead wood cavities, with nest structure varying from straight to branching and containing up to 10 cells. Each cell is provisioned with 6-8 paralyzed flies for a single larva.

Females excavate or modify nest tunnels in dead wood using mandibles; nesting aggregations can be large and dense with multiple females sometimes sharing a common nest entrance. Adults are strongly associated with umbellifer flowers for both nectar and hunting prey.

Predator of medium-sized Diptera; pollinator and flower visitor of umbellifer plants. Contributes to biological control of fly populations.

Potential biocontrol agents for pest fly populations; no significant negative impacts to humans. Nest construction in wooden structures may occasionally occur but is not considered economically damaging.

• AnacrabroSimilar black and yellow coloration; distinguished by very concave underside of abdomen and prey preference for plant bugs (Miridae) rather than flies
• LesticaSimilar appearance in tribe Crabronini; distinguished by abdominal structure and nesting behavior
• CrabroSimilar appearance in tribe Crabronini; distinguished by morphological details of abdomen and antennae

• digger wasp
• solitary wasp
• wood-nesting
• fly predator
• umbellifer visitor

• BugGuide
• Wikipedia
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
• Bug Eric: Wasp Wednesday: Anacrabro ocellatus
• The genome sequence of a digger wasp, Ectemnius lituratus (Panzer,1805).
• The genome sequence of a digger wasp, Ectemnius continuus (Fabricius, 1804).